Disclosed is a body fat measurement apparatus (1) comprising an impedance measurement electrode system including a pair of current supplying electrodes (7a,7b) and a pair of voltage measurement electrodes (8a,8b), those electrodes adapted for contact with peripheral surface of abdomen of a person under test to measure impedance of the abdomen, on the basis of which an index of body fat of the person under test is calculated. According to the present diclosure, said apparatus further comprising: an electrode support unit (3); a lateral width measurement unit (4a,4b); and an arithmetic unit (2), wherein said electrode support unit supports the impedance measurement electrode system so that the electrodes thereof are contact with front surface of the abdomen of the person under test for measuring impedance of the abdomen, said lateral width measurement unit (4a,4b) measures lateral width of the abdomen of the person under test, and said arithmetic (2) unit calculates the index of body fat of the person under test on the basis of the impedance of the abdomen and the lateral width.